This program project entitled "Immunobiology and Pathogenesis of Infections in Infants", formalizes an established productive relationship between the Divisions of Pediatric Infectious Disease and of Pediatric Immunology and the Department of Microbiology of the University of Texas Health Science Center, Dallas, Texas. The proposed multidisciplinary program is comprised of six projects, each directed by a scientist who has demonstrated expertise in the targeted research area. Modern molecular immunobiologic techniques will be used to isolate and identify specific surface components or products of bacterial cells in order to determine their role in the pathogenesis of disease in infants and children. We will explore the means by which these microbial structures bind to receptors on host cells, cause an inflammatory response in animal models or induce an immunologic response in congenitally infected fetuses (neonates), in infants and their mothers and in children. The unifying theme of the program project is the examination of genetically determined and developmental factors that modulate the host's response and account for the unique susceptibility of infants and children for disease caused by Haemophilus influenzae, Neisseria meningitidis, Treponema pallidum, group B Streptococcus, enterotoxin-producing Escherichia coli and Pseudomonas aeruginosa. Principles and techniques derived from the laboratory will be applied to the clinic by the program directors who are members of the Division of Pediatric Infectious Disease (Clinical Core) utilizing facilities of Parkland Memorial Hospital and Children's Medical Center of Dallas, both affiliated with the Health Science Center complex. Six projects are proposed and these will be conducted by six independent investigators who will effectively interact with each other, share some laboratory equipment (Laboratory Core, Core A) and collaborate with the program directors who comprise the Clinical Core (Core B). An administrative assistant (Administrative Core, Core C) will be responsible for ordering supplies, maintaining the financial records and performing secretarial functions.